在 java 中制作 InputStream 副本的最佳方法是什么
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What is the best way to make a copy of an InputStream in java
提问by Ankur
Possible Duplicate:
How to make a deep copy of an InputStream in Java ?
I have an InputStream object and I want to make a copy of it. What is the best way to do this?
我有一个 InputStream 对象，我想复制它。做这个的最好方式是什么？
The data is not coming from a file but as the payload of a http form being sent from a web page, I am using the Apache Commons FileUpload lib, my code which gives me the InputStream looks like this: ...
数据不是来自文件，而是作为从网页发送的 http 表单的有效负载，我使用的是 Apache Commons FileUpload 库，我的代码提供了 InputStream，如下所示：...
InputStream imageStream = null;
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
List items = new ArrayList();
items = upload.parseRequest(request);
Iterator iter = items.iterator();
while (iter.hasNext()) {
FileItem item = (FileItem) iter.next();
if (item.isFormField()) { // this is subject Id
if (item.getFieldName().equals("subId")) {
subId = Integer.parseInt(item.getString());
System.out.println("SubId: " + subId);
}
} else {
imageStream = item.getInputStream();
}
}
What is the best way to get a duplicate/copy of imageStream?
获取 imageStream 副本/副本的最佳方法是什么？
回答by Flavio
If you want to be able to read the stream again, I think your best option is to wrap the InputStreamin a BufferedInputStream, and then use the BufferedInputStreammark()and reset()methods. The InputStreamyou have will probably not support them directly, since as far as I understood it receives data from the web.
如果您希望能够再次读取流，我认为您最好的选择是将 包装InputStream在 a 中BufferedInputStream，然后使用BufferedInputStreammark()和reset()方法。在InputStream你有可能不会直接支持他们，因为据我的理解是从网络接收数据。
回答by Lukas Eder
The best way of "copying" your input stream is to use commons-io. Since you're using commons fileupload alread, that additional dependency won't hurt:
“复制”输入流的最佳方式是使用 commons-io。由于您已经使用了 commons fileupload，因此额外的依赖不会受到影响：
Be aware though, that you cannot really "copy" a stream. You can only "consume" it (and then maybe store the contents in memory, if you want that)
但是请注意，您不能真正“复制”流。您只能“使用”它（然后可以将内容存储在内存中，如果您愿意的话）
